Numerical Experiment of Cold Flakes Behavior in Shot Sleeve of Aluminum Alloy Die Casting

With growing needs for thin wall and weight-saving products, production quantity of aluminum alloy is increasing more and more. It is important to control casting conditions in order to obtain sound and highly functional products. The present study focused on the cold flakes in the shot sleeve of aluminum alloy die casting. The solidified layer generated in the early stages of die casting when the molten metal is charged in contact with the bottom of the sleeve, and exfoliated with the movement of the plunger, yielding the cold flakes. If the cold flakes flow into the cavity region, the mechanical properties of product will deteriorate. To predict casting defects caused by cold flakes, numerical simulation was performed to analyze the dynamic behaviors of the cold flakes. The conditions for the generation of the cold flakes and the equations of motion including gravity, buoyancy, fluid drag were established in the present study. The movement of cold flakes was traced by solving momentum equations by the Runge-Kutta-Gill method. The calculated results showed that the behavior of cold flakes vary according to conditions such as initial temperature of molten metal, sleeve temperature, etc.